1. Field of the Invention
The present invention relates to a fuel limitation device for a diesel engine with a supercharger and particularly concerns a technique for inhibiting fuel increase at the time of quick acceleration by a diaphragm-type boost actuator, while securing a starting fuel increase.
2. Explanation of Related Art
There are conventionally known examples of the fuel limitation device for an engine with a supercharger such as shown in FIG. 11 (prior art 1) and in FIG. 12 (prior art 2).
As shown in FIG. 11, the prior art 1 comprises a fuel meter 21 of a fuel injection pump for an engine (E) with a supercharger, made movable for fuel metering through a double governor lever 14 of a centrifugal governor 10. A swing lever 31 is supported by a pivot axis (Q) and has a power input point (J) which engages with an output rod 30 of a diaphragm-type boost actuator 26. The swing lever 31 has a power output point (K) which faces the fuel meter 21 from a fuel increase side (R) of the fuel meter 21. If the boost actuator 26 operates in response to a delayed rise of a pressure (P) supercharged to the engine (E), the power output point (K) of the swing lever 31 inhibits the fuel meter 21 from moving for fuel increase.
The boost actuator 26 projects the output rod 30 with the supercharged pressure (P) against a return spring 28. Then it limits an excessive fuel supply caused by the delayed rise of the supercharged pressure (P) attributable to a rotation delay of the supercharger (turbo-charger) at the time of quick acceleration and the like to thereby prevent the generation of black smoke and the wasteful fuel consumption. Further, there is disposed a push rod (M) which strongly pushes out the fuel meter 21 to a starting fuel increase position against the return spring 28 of the boost actuator 26 when starting the engine (E). Here, in FIG. 11, numerals 2 and 3 designate a turbine and a compressor of the supercharger. Numeral 4 indicates a waste gate valve which reduces an excessive exhaust pressure caused by exhaust gas (C) produced at the time of a high-speed operation. Numerals 5, 6, 8, 11, 12 and 13 show an intake pipe, an exhaust pipe, a supercharged pressure communication pipe, a speed control operation lever, a speed control lever, and a governor spring, respectively. Numerals 14a and 14b indicate a first lever and a second lever forming a double governor lever 14. Numeral 15 designates a pivot axis of the governor lever 14. Numerals 16, 18 and 46 show a torque-up device, a start spring and a governor sleeve, respectively.
As shown in FIG. 12, the prior art 2 comprises a fuel meter 21 of a fuel injection pump for an engine with a supercharger, made movable for fuel metering through a double governor lever 14 of a centrifugal governor 10. A swing lever 31 is supported by a pivot axis (Q) and has a power input point (J) which engages with an output rod 30 of a diaphragm-type boost actuator 26. The swing lever has a power output point (K) which faces the fuel meter 21 from a fuel increase side (R) of the fuel meter 21. If the boost actuator 26 operates in response to a delayed rise of a pressure (P) supercharged to the engine (E), the power output point (K) of the swing lever 31 inhibits the fuel meter 21 from moving for fuel increase. An actuator 40 displaces the pivot axis (Q) to position the power output point (K) of the swing lever 31 on the fuel increase side (R) or a fuel decrease side (L). When making a cold start of the engine, the actuator 40 has its output rod 35 retracted to move the fuel meter 21 for fuel increase by the power output point (K) of the swing lever 31, thereby cancelling a fuel limitation function of the boost actuator 26. After the engine has started, the boost actuator 26 maintains the fuel limitation function.
According to the prior arts 1 and 2, it is possible to prevent the generation of black smoke and the wasteful fuel consumption by limiting the excessive fuel supply attributable to the delayed rise of the supercharged pressure (P). However, they have to be still improved on the following points.
When starting the engine, since no boost pressure acts on the boost actuator 26 and the output rod 30 is retracted, the power output point (K) of the swing lever 31 prevents the fuel meter 21 of the fuel injection pump from moving to a starting fuel increase position.
Then the prior art 1 requires to separately provide a push rod (M) which pushes out the fuel meter 21 to the starting fuel increase position against the return spring 28 of the boost actuator 26 when starting the engine. This needs a strong driving force which pushes out the push rod (M) against the return spring 28 of the boost actuator 26. On the other hand, if the fuel meter 21 always exists at the starting fuel increase position when starting the engine, excessive fuel is supplied at the time of making a warm start to result in entailing a problem of generating black smoke and consuming fuel wastefully.
Further, the prior art 2 retracts the output rod 35 of the actuator 40, thereby enabling the power output point (K) of the swing lever 31 to move for fuel increase when starting the engine. Therefore, it can solve the disadvantage of the prior art 1. However, the output portion 17 of the governor lever 14 unseparably engages with the fuel meter 21 of the fuel injection pump. This requires setting a resilient force of the return spring 28 of the boost actuator 26 to have such a strength as substantially balancing an extension force of the governor spring 13 at the time of quick acceleration so that the boost actuator 26 can inhibit the fuel meter 21 from moving for fuel increase at the time of the quick acceleration. Correspondingly, a diaphragm 27 must have its pressure receiving area increased. This makes the boost actuator 26 large as a whole as well as in the prior art 1.
Under the above circumstance, the present invention has been creased. It has an object to secure an ability of starting an engine by a boost actuator having a simple and inexpensive downsized structure without requiring a driving force strong enough to overcome the return spring of the boost actuator for placing the fuel meter at the starting fuel increase position. Further, it has another object to provide a fuel limitation device which inhibits the excessive fuel supply when making the warm start and prevents the generation of black smoke and the wasteful fuel consumption.
The present invention has the same basic structure as the prior art 1 (see FIG. 11), for example, as shown in FIGS. 1, 2, 8, 9 and 10.
A fuel meter 21 of a fuel injection pump for an engine with a supercharger is made movable for fuel metering through a governor lever 14. A swing lever 31 is supported by a pivot axis (Q) and has a power input point (J) which engages with an output rod 30 of a diaphragm-type boost actuator 26. The swing lever 31 has a power output point (K) which faces the fuel meter 21 from a fuel increase side (R) of the fuel meter 21. If the boost actuator 26 operates in response to a delayed rise of a pressure (P) supercharged to the engine (E), the power output point (K) of the swing lever 31 inhibits the fuel meter 21 from moving for fuel increase.
In a fuel limitation device for an engine with a supercharger having the foregoing basic structure, an invention as set forth in claim 1 (a first invention), for example, as shown in FIGS. 1, 2 and 8, connectably and separably opposes an output portion 17 of the governor lever 14 to the fuel meter 21 from a fuel increase side (R) and urges the fuel meter 21 by a start spring 18 toward a starting fuel increase side. An actuator 40 displaces the pivot axis (Q) to position the power output point (K) of the swing lever 31 on the fuel increase side (R) or a fuel decrease side (L). When making a cold start of the engine, the fuel meter 21 is received at a starting fuel increase position (St) by the power output point (K) positioned on the fuel increase side (R). On the other hand, when making a warm start of the engine, the fuel meter 21 is received at a starting fuel decrease position (Ls) by the power output point (K) positioned on the fuel decrease side (L). Here, the cold start means to start the engine before it becomes warm and the warm start means to start it in a warm environment (including the start after it has become warm to wait as it is, which is applicable to the later recitation).
In a fuel limitation device for an engine with a supercharger having the foregoing basic structure, an invention as set forth in claim 2 (a second invention), for example, as shown in FIGS. 9 and 10, opposes connectably and separably an output portion 17 of the governor lever 14 to the fuel meter 21 from the fuel increase side (R) and urges the fuel meter 21 by a start spring 18 toward a starting fuel increase side. An actuator 40 loaded on the output rod 30 of the boost actuator 26 reversely displaces the power input point (J) of the swing lever 31 to position the power output point (K) of the swing lever 31 on the fuel increase side (R) or a fuel decrease side (L).
When making the cold start of the engine, the power output point (K) positioned on the fuel increase side (R) receives the fuel meter 21 at a starting fuel increase position (St). On the other hand, when making the warm start of the engine, the power output point (K) positioned on the fuel decrease side (L) receives the fuel meter 21 at a starting fuel decrease position (Ls). Here, to reversely displace by the actuator 40 means that the output rod 30 of the boost actuator 26 operates in a direction reverse to a direction in which the actuator 40 loaded on the output rod 30 operates.
In the fuel limitation device for the engine with the supercharger as set forth in claim 1 or 2, an invention of claim 3 constructs the actuator 40 by a temperature sensitive actuator 32.
In the fuel limitation device for the engine with the supercharger as set forth in claim 3, an invention of claim 4 makes the temperature sensitive actuator 32 project the output rod 35 owing to temperature sensitive volume expansion of a wax accommodated in a vessel 34.
In the fuel limitation device for the engine with the supercharger as set forth in claim 1 or 2, an invention of claim 5 provides a temperature sensor 41 which senses the environment temperature of the engine and an electric driving circuit 42 which operates the actuator 40 by a sensed signal (N) sent from the temperature sensor 41. When making the cold start of the engine, the actuator 40 does not operate. But when making the warm start of the engine, the actuator 40 operates.
In the fuel limitation device for the engine with the supercharger, an invention of claim 6 constructs the actuator 40 by a piston actuator 44 which operates with an engine intake negative pressure, an engine back pressure or a lubricant pressure. When starting the engine, the piston actuator 44 does not operate to result in receiving the fuel meter at the starting fuel increase position (St) by the power output point (K) of the swing lever 31.
The present invention brings forth the following functions and effects.
(a) According to the invention of claim 1 (a first invention), in the fuel limitation device for the engine with the supercharger having the foregoing basic structure, the output portion 17 of the governor lever 14 is connectably and separably opposed to the fuel meter 21 from the fuel increase side (R) and the start spring 18 urges the fuel meter 21 toward the starting fuel increase side. Therefore, the diaphragm-type boost actuator 26 can be adapted to produce a small output and be made compact.
In a normal operation, the fuel meter 21 of the fuel injection pump is urged by the start spring 18 toward the fuel increase side and follows the operation of the output portion 17 of the governor lever 14. On the other hand, when strongly pulling the governor lever 14 toward the fuel increase side (R) by a governor spring force through the speed control lever 12 at the time of quick acceleration, the output portion 17 of the governor lever 14 separates from the fuel meter 21 and moves toward the fuel increase side (R). And a governing force (GF) does not act on the fuel meter 21 but only an urging force of the start spring 18 acts thereon. At this time, it is sufficient setting a resilient force of the return spring 28 of the boost actuator 26 to have a strength substantially balancing the urging force of the start spring 18 in order that the boost actuator 26 can exert its boost function to inhibit the fuel meter 21 from moving for fuel increase. In short, it is possible to reduce the resilient force of the return spring 28 of the boost actuator 26 much more than the prior arts, which results in the possibility of remarkably decreasing the pressure receiving area of the diaphragm 27 which resists it. In consequence, the boost actuator 26 can be adapted to produce a small output and be made compact.
(b) In addition to the function and effect (a), the invention of claim 1 (the first invention) brings forth the following ones.
The actuator 40 displaces the pivot axis (Q) of the swing lever 31 to position the power output point (K) of the swing lever 31 on the fuel increase side (R) or the fuel decrease side (L). Therefore, when making the cold start of the engine, the start spring 18 pushes out the fuel meter 21 to the starting fuel increase position (St). In short, this does not requires the push rod (M) (see prior art 1) which pushes out the fuel meter 21 to the starting fuel increase position (St) against the return spring 28 of the diaphragm-type boost actuator 26. This results in a simple and inexpensive structure.
(c) According to the invention of claim 1 (the first invention), when making the cold start of the engine, the power output point (K) positioned on the fuel increase side (R) receives the fuel meter 21 at the starting fuel increase position (St). When making the warm start of the engine, the power output point (K) positioned on the fuel decrease side (L) receives the fuel meter 21 at the starting fuel decrease position (Ls). Therefore, it is possible to inhibit the excessive fuel supply when making the warm start of the engine, thereby preventing the generation of black smoke or the like, while securing an ability of making the cold start of the engine.
More specifically, when making the cold start of the engine, the fuel meter 21 of the fuel injection pump is received at the staring fuel increase position (St) by the power output point (K) positioned on the fuel increase side (R). This supplies fuel in an amount necessary enough to make the cold start of the engine, thereby securing the ability of making the cold start.
Further, when making the warm start, the fuel meter 21 of the fuel injection pump is received at the starting fuel decrease position (Ls) by the power output point (K) positioned on the fuel decrease side (L). This inhibits the excessive fuel supply to result in preventing the generation of black smoke and the like.
(d) The invention of claim 2 (a second invention) as well as the first invention connectably and separably opposes the output portion 17 of the governor lever 14 to the fuel meter 21 from the fuel increase side (R) and urges the fuel meter 21 by the start spring 18 toward the starting fuel increase. When making the cold start of the engine, the fuel meter 21 is received at the starting fuel increase position (St) by the power output point (K) positioned on the fuel increase side (R). When making the warm start of the engine, the fuel meter 21 is received at the starting fuel decrease position (Ls) by the power output point (K) positioned on the fuel decrease side (L). Therefore, it brings forth the same functions and effects (a) and (c) as the first invention does.
(e) In addition, according to the invention of claim 2 (the second invention), for example, as shown in FIGS. 9 and 10, the actuator 40 loaded on the output rod 30 of the boost actuator 26 reversely displaces the power input point (J) of the swing lever 31 to position the power output point (K) of the swing lever 31 on the fuel increase side (R) or the fuel decrease side (L). When making the cold start of the engine, the start spring 18 pushes out the fuel meter 21 to the starting fuel increase position (St). In short, this does not require the push rod (M) (prior art 1) which pushes out the fuel meter 21 to the starting fuel increase position (St) against the return spring 28 of the diaphragm-type boost actuator 26, which results in a simple and inexpensive structure.
(f) In the fuel limitation device for the engine with the supercharger as set forth in claim 1 or 2, the invention of claim 3 constructs the actuator 40 by the temperature sensitive actuator 32. Accordingly, it can inhibit the excessive fuel supply when making the warm start, thereby preventing the generation of black smoke or the like, while securing the ability of making the cold start.
(g) According to the invention of claim 4, in the fuel limitation device for the engine with the supercharger as set forth in claim 3, the temperature sensitive actuator 32 projects the output rod 35 owing to the temperature sensitive volume expansion of the wax accommodated in the vessel 34. This can put the temperature sensitive actuator 32 into practice with a simple structure and at a low cost.
(h) In the fuel limitation device for the engine with the supercharger as set forth in claim 1 or 2, the invention of claim 5 provides the temperature sensor 41 which senses the environment temperature of the engine, and the electric driving circuit 42 which operates the actuator 40 by the sensed signal (N) sent from the temperature sensor 41. When making the cold start, the actuator 40 does not operate, and when making the warm start, it operates. This can limit the excessive fuel supply when making the warm start, thereby preventing the generation of black smoke and the wasteful fuel consumption, while assuring the ability of making the cold start of the engine.
(i) In the fuel limitation device for the engine with the supercharger as set forth in claim 1 or 2, the invention of claim 6 constructs the actuator 40 by a piston actuator 44 which operates with an engine intake negative pressure, an engine back pressure or a lubricant pressure. When starting the engine, the piston actuator 44 does not operate to thereby receive the fuel meter 21 at the starting fuel increase position (St) by the power output point (K) of the swing lever 31. Consequently, this cancels the fuel limitation function of the boost actuator 26 irrespective of the engine""s environment temperature and therefore secures the starting fuel increase to facilitate the engine start.
For example, like the engine generator and so on, in the case where the engine has a large dragging load, even when making the warm start, failure to start occurs unless the starting fuel increase is secured. However, the present invention can solve the start failure occurring in the case where the engine has a large dragging load.